/*
 * Copyright (C) 2013 Square, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.msimw.retrofit2x.retrofit;


import java.lang.invoke.MethodHandles.Lookup;
import java.lang.reflect.Constructor;
import java.lang.reflect.Method;
import java.util.concurrent.Executor;

class Platform {
  private static final Platform PLATFORM = findPlatform();

  static Platform get() {
    return PLATFORM;
  }

  private static Platform findPlatform() {
    try {
      Class.forName("java.util.Optional");
      return new Java8();
    } catch (ClassNotFoundException ignored) {
    }
    return new Platform();
  }

   Executor defaultCallbackExecutor() {
    return null;
  }

  CallAdapter.Factory defaultCallAdapterFactory( Executor callbackExecutor) {
    if (callbackExecutor != null) {
      return new ExecutorCallAdapterFactory(callbackExecutor);
    }
    return DefaultCallAdapterFactory.INSTANCE;
  }

  boolean isDefaultMethod(Method method) {
    return false;
  }

   Object invokeDefaultMethod(Method method, Class<?> declaringClass, Object object,
       Object... args) throws Throwable {
    throw new UnsupportedOperationException();
  }

  // Only classloaded and used on Java 8.
  static class Java8 extends Platform {
    @Override boolean isDefaultMethod(Method method) {
      return false;
    }

    @Override Object invokeDefaultMethod(Method method, Class<?> declaringClass, Object object,
         Object... args) throws Throwable {
      // Because the service interface might not be public, we need to use a MethodHandle lookup
      // that ignores the visibility of the declaringClass.
      Constructor<Lookup> constructor = Lookup.class.getDeclaredConstructor(Class.class, int.class);
      constructor.setAccessible(true);
      return constructor.newInstance(declaringClass, -1 /* trusted */)
          .unreflectSpecial(method, declaringClass)
          .bindTo(object)
          .invokeWithArguments(args);
    }
  }

}
